4 SOPER— GEOLOGY OF PARAHYBA 



the low, plateau-like chapadas mentioned above. In the eastern part 

 of Parahyba the coastal sediments are scarred by short streams 

 which have narrow, fertile valleys and steep banks, where erosion 

 has cut deeply into the soft beds. 



The plateau region can be described briefly as a great rolling 

 plain of hard, crystalline rock, covered irregularly by a growth of 

 caatinga, dense or sparse according to the character and degree of 

 decomposition of the underlying rocks. It covers by far the greater 

 portion of the two states and ranges from an elevation of lOO meters 

 near the contact with the sediments, to 300 meters further inland. 

 It is in this region, locally known as the " alto sertao," that drought 

 is most severely felt. 



Rising abruptly from this undulating plateau and attaining a 

 height of from 500 to 600 meters, is a series of serras which form 

 the only relief in the monotonous topography. Most marked of 

 these serras is the Planalto de Borborema with a mean elevation of 

 about 500 meters, which reaches from the southern portion of Rio 

 Grande do Norte, clear across the central portion of Parahyba and 

 forms a part of the boundary of that state with Pernambuco. In 

 the vicinity of Campina Grande it has a width of more than 100 

 kilometers but narrows to the north of there. The Serras Canna- 

 brava, Jabitaca, Baixa Verde and Teixeira form a part of the 

 boundary referred to above. 



From the Serra Teixeira there is a low line of mountains 

 stretching away to the eastern part of Ceara. Some of the larger 

 ones are the Serra Mellado, Serra Catharina and the Serra do Vital. 

 There are several more, smaller and without names, significant only 

 in that they form a part of a general structural feature. The 

 Serra Santa Catharina is the most important of the mountains 

 named and reaches a height of about 650 meters. To the north of 

 this mountain line, beginning near Souza and stretching in a north- 

 east direction almost to Catole do Rocha, is a long mountain called 

 the Serra Commissario. I did not cross this serra, but from a 

 distance it appeared to be a series of small buttes rather than one 

 great mountain. 



Still further north of the Serra Commissario, and forming 



